I think you need to pull first.
I have started to take everything with me I need, stash the rest in the woods, and leave my truck unlocked when I go. I have a cheap stereo, so no worries there. Anyone else do this, or does it just sound crazy? I can't think of any other way, except that once when at a trailhead I saw someone leave a note that said, "Nothing of value in vehicle". Don't know if any of that helps, but I've never been broken into (besides outside my home).